Chain wrench



NOV. 29, 1966 J. LAIRD, JR 3,288,001

CHAIN WRENCH Original Filed June 8, 1964 4 Sheets-Sheet l FIGI.

INVENTOR? JONATHAN L. LA |RD,JR

ATTYS Nov. 29, 1966 J. L. LAIRD, JR

CHAIN WRENCH 4 Sheets-Sheet 2 Original Filed June 8, 1964 FIGS.

INVENTOR! JONATHAN L. ,LAIRD QJR CHAIN WRENCH 4 Sheets-Sheet 5 INVENTOR'.

M JONATHAN L. L.AIRD,JR.

ATTYS' Nov. 29, 1966 J. 1.. LAIRD, JR

Original Filed June 8, 1964 Nov. 29, 1966 J. L. LAIRD, JR 3,288,001

CHAIN WRENCH Original Filed June 8, 1964 4 Sheets-Sheet 4 FIG] ATTYS 1 3 I mvzmon; BY JONATHAN L. LAIRDPJR;

United States Patent Continuation of application Ser. No. 373,242, June 8,

1964. This application May 9, 1966, Ser. No. 548,800 7 Claims. (Cl. 81-68) This is a continuation of application Serial No. 373,242, filed June 8, 1964, now abandoned.

The present invention relates to improvement in chain wrenches and more specificallyto wrenches in which a chain of links of special construction affords a positive grip uniformly around an article for applying torque thereto, regardless of the articles external shape while because of the specific structure of the wrench a special friction effect insures positive engagement of the links with the article to which the wrench is applied.

As is well known to those skilled in the art, the use of large Stillson or heavy monkey wrenches on pipes and their associated fittings oftentimes distorts, warps or crushes the pipe or fitting to where it may not be capable of further use. Further, many times it is desired to use a heavy wrench on a pipe or fitting in a difiicult location such as along the sides of walls, floors or in corners, and the size of the wrench necessary to obtain a firm grip upon the pipe or fitting makes it difiicult to obtain a purchase on the fitting with a standard pipe or Stillson wrench. Further, if it is desired to hold a pipe to prevent its turning within a fitting or the like, oftentimes the only place of obtaining a purchase on the pipe is on its threads, and a standard Stillson or pipe wrench will ruin the threads.

In view of the above, it is an object of the present invention to provide a chain wrench which applies even pressure on the greater part of the circumference of an article being gripped thereby avoiding warping, distorting or crushing of the pipe or fitting.

Another object of the present invention is to provide a chain wrench which may be used in difficult places such as on pipes or fittings located adjacent walls or in other difficult locations.

Still another object of the present invention is to provide a wrench with numerous contact or gripping points so that it may be used directly on pipe threads when necessary and in so doing cause little harm to the pipe threads. I

Another object of the present invention is to provide a special friction device on the wrench itself to insure the tight gripping of the chain against any surface to which it is applied and to provide the chain wrench with a ratchet-like action.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary plan view of a chain wrench, constructed in accordance with the present invention, and gripping a portion of an article;

FIG. 2 is a side view of the chain wrench illustrated in FIG. 1;

FIG. 3 is an enlarged fragmentary perspective view of a portion of the chain illustrated in FIG. 2;

FIG. 4 is a fragmentary plan view of another embodiment of a chain Wrench constructed in accordance with the present invention, and gripping a portion of an article;

FIG. 5 is a side view of the wrench illustrated in FIG. 4;

FIG. 6 is a plan view of a pair of chain wrenches constructed in accordance with the present invention and illustrating their use with a power assist; and

FIG. 7 is a side view of the apparatus illustrated in FIG. 6.

Referring now to the drawings and especially FIGS.

1 and 2, a chain wrench is therein illustrated comprising a handle member 10 connecting a bifurcated head 11, the bifurcated head having spaced offset cars 12 and 13 respectively to receive therebetween the terminal link or depending offset portion 9 of a chain 15 secured to the cars by a pin 14. As illustrated, the offset portion 9 helps to insure maximum circumferential placement of the chain 15 relative to a work piece. At the base of the head 11, connected to the ears 12 and 13 via a pivot pin 21 is a special friction lever 20, in the illustrated instance a swingable cam 22 which, after the chain 15 passes around a workpiece to be torqued such as a pipe 28, bears against the non-working or non-toothed side of the chain to increase the leverage of the chain 15 against the pipe 28.

In accordance with the invention, the chain 15 comprises transverse rows 15a of link plates 16, each link plate having at least a forward and rear pointed tooth 17 and 18 respectively, both teeth being disposed on the side of the row which engages the workpiece 28. Further, the forward and rear teeth, 17 and 18, have apertures therein. Asillustrated in the drawings, the adjacent rows are connected together by link pins 19 passing through the apertures of the forward teeth 17 in one row and the rearward teeth 18 of the other row. Thus the link plates of one row are interdigitated with respect to the link plates in the adjacent row, and as may be seen in FIG. 3,

in the present instance the link plates of one row alter-' nating with the link plates in the adjacent row. This insures that when the chain assumes a position circumscribing an object such as a pipe or the like 28, the rearward teeth 18 of the link plates of one row are angularly disposed to the forward teeth 17 in the link plates connecting adjacent rows thus giving a scissors-like appearance to the teeth (see FIG. 3). Thus when the chain is stretched taut on a straight line the points of the adjacent teeth are aligned but when the chain circumscribes an object such as the pipe 28, the points of adjacent teeth of connected links turn to different radial positions relative to each other and thus engage the work at different points along its circumference.

In accordance with another feature of the invention,

the swingable cam 22 has a camming surface 23 which bears against the back or non-Working surface of the chain when the chain is circumscribing an article. By affording to the cam 22 movability, relative to the head 11, differences in diameter of the objects to be encom-' passed by the chain and gripped thereby may be compensated for.

or total leverage greater than that which could be realized merely by clamping the chain at its extended terminus or along the portion of the chain not circumscribing theobject.

Thus when the chain encircles an article having corners,

for example hexagonal nuts or the like, the recesses or depressions between the teeth accommodate the corners and permit the link plates or rows of links which turn the corner or corners to establish an effective working relationship and effect engagement at the straight stretches of the chain. This combined with the special frictional leverage exerted by the cam member 22, insures a positive gripping action at many surfaces circumscribing the exterior of the member or object being clamped rather than just two as would be true with a pipe or monkey wrench.

In order to move the Wrench into more diflicult locations to remove piping and associated fittings, the head may be made with a flexible portion While the camming member may be made coextensive with another portion of the head. To this end a wrench constructed in accordance with the invention and embodying this feature Patented Nov. 29, 1966* The provision of the cam 22 and its movability with respect to the chain provides a compound link plates 36 are inclined in the direction in which the I chain 35 is torqued when the chain is positioned circumscribing a workpiece. The purpose of inclining the teeth 37 and 38 of the link plates 36 in this direction, is to provide a digging action or gripping action in this direction. At the base 31b of the head 31, is a fixed cam 34 having a camming surface 34a which adjusts automatically to the size of an object being torqued by applying pressure against the non-toothed or non-working surface of the chain 35 when circumscribing a pipe or other workpiece 39. The reason for the camming surface automatically adjusting to the size of an object is because'the bifurcated portion 31a is loosely pivoted with respect to the cam.

Where extremely heavy pipe and associated fittings must be separated or tightened it is desirable to provide a power assist to effect the necessary torque. To this end, and in accordance with another feature of the invention, a pair of wrenches such as those previously described with reference to FIGS. 1-5, may be disposed in opposite torque relationship on the pipe and fitting respectively and the power assist used to turn one wrench against the other wrench. A pair of wrenches constructed in accordance with the present invention are illustrated in FIGS. 6 and 7.

In the illustrated embodiment, a pair of oppositely torqued wrenches designated 40 and 60-respectively, are shown gripping a pipe 80 and a fitting 81 for tightening the fitting to the pipe. As before, each wrench respectively comprises a handle member (41 and 61), connected to a head (42 and 62), having a flexible bifurcated por-' tion (42a and 62a) and a fixed base portion (42b and 62b). The bifurcated portions 42a and 62a have spaced offset ears 43, 44 and 63, 64 to receive therebetween chains 45, 65 which are loosely pivoted to the base por- 1 tions 42b and 62b respectively by pins 46 and 66. The

and 67 having associated camming surfaces 47a and re:

spectively' 67a. The cams adjust automatically to the size of the object being torqued by applying pressure against the back or non-working surface of the respective chains 45 and 65 when circumscribing the pipe 80 and fitting .81. The reason for the camming surfaces automatically adjusting to the size of the object is because the bifurcated portions 42a and 62a are loosely pivoted with respect to the cam permitting the cam to adjust at its point of contact to the non-working surface of the respective chains.

Connected between the handles 41 and 61 of the wrenches 40 and 60 respectively is a power drive unit 70 of a standard type. The power drive unit may be hydraulic, air or mechanically operated so as to cause relative movement of one handle with respect to the other. In the present instance the drive unit 70 is hydraulically operated having a double acting piston within the cylinder or casing 71 and operable, by moving hydraulic fluid into the hydraulic inlet 72, to move the head 42b into the broken line position, as illustrated in FIG. 7. A'holding member in the present instance a separate handle element 75, may be connected to the base portion 62b so as to insure movement or turning of only the desired member,

i.e., in the present instance, pipe or fitting.

advantageous to provide a special chain which will permit an increased number of teeth to engage the large articles. Such a chain is best illustrated in FIG. 7 wherein transverse rows 65a of link plates 69 have atleast two pointed In the instance of large pipes or fittings, it may be adjacent teeth 67 and 68 disposed on the same side. of

the row. As before, adjacent rows are connected togetherby link plates in adjacent rows being interdigitated;

in the present instance alternating. To insure the teeth will provide a maximum grip on large objects, the teeth. 67 and 68, carried by each link plate 69 and disposed.

on the same sideof the link plate, are angularly inclined towards each other. assumes a position circumscribing large objects wherein the chain has very little curvature, the teeth of the link plates of one row are angularly disposed to the teeth in the connecting adjacent rows thus giving a scissors-like appearance to the teeth even when the chain is in a substantially flat or straight position.

It should be realized that the chain of the present invention will permit of any transverse width which may be required, and thus the number of pressure points around a fitting may be increased or decreased. The advantage of having a great number of pressure points cannot be overemphasized in situations where heavy pressure is required in order to break or make a tight fitting. An example of the number of pressure points that may be obtained by the use of chains constructed in accordance with the present invention, may be realized with the use of a chain such as that illustrated in FIG. 3. As may be noted, each row 15a has 30 individual points or teeth and if the distance from center to center of the link pins is /2 inch and if the pipe upon which the wrench is to be used is a two inch pipe, a total of 225 staggered pressure points may be arranged circumscribing approximately of the pipe, instead of only two localized pressure areas as would be possible with the Stillson or monkey wrench.

In summary the present invention provides a chain wrench which is extremely flexible in operation, may be used in diflicult locations, and provides a maximum of contact or pressure points around a fitting or the like to be tightened or to be loosened. It should be noted that,

the cam, in all of the embodiments, when the wrench is gripping a workpiece, causes the chain to be tensioned upon the article thereby increasing the grip of the wrench.

Further, the special arrangement of the special friction device on the wrench itself insures the tight gripping of the chain and easy accommodation to any size or shape article to which the wrench is to be applied.

Although the invention has been described with a cer tain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in details of construction and the combination and arrangement of parts may be madewithout departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. In a chain wrench comprising .a head having a handle connected thereto, said head including a bifurcated:

said bifurcation intermediate said cam and said connecting means whereby said chain substantially circumscribes and grips with said teeth a workpiece to which torque is to be applied by said wrench; the improvement wherein said cam includes a smooth camming surface for bearing,

against the side opposite said toothed side of said chain in the portion thereof circumscribing said workpiece to thereby securely anchor said chain against said workpiece and .said cam, said camming surface being of sufficient length to permit said cam to be the sole anchoring means for said Wrench upon torque being applied to. workpieces having differing diameters.

This insures that when the chain jacent rows and wherein said means connecting said chain to said head comprises a depending offset portion to insure maximum circumferential engagement of said chain with respect to a workpiece.

3. A wrench in accordance with claim 2 wherein all of the teeth on said link plates are disposed at the same angle relative to said plates whereby upon said chain assuming a position circumscribing said workpiece, said teeth of the links in one row are angularly disposed to the teeth of the plates in an adjacent row.

4. A wrench in accordance with claim 2 wherein each link plate has a pair of teeth inclined towards each other whereby upon said chain assuming a substantially straight position said teeth of the links in one row are angularly disposed to the teeth of the plates in an adjacent row.

5. A wrench in accordance with claim 2 wherein each of the teeth on said link plates is inclined in a direction to cause digging of said teeth into said object as it is being torqued.

6. A wrench in accordance with claim 2 wherein said cam is pivotably connected to said head so as to auto- References Cited by the'Examiner UNITED STATES PATENTS 1,316,875 9/1919 Budlong 8167 2,665,604 I/ 1954 Robertson 8166 FOREIGN PATENTS 1,075,771 4/1954 France.

801,266 12/ 1950 Germany. 188,392 11/ 1922 Great Britain.

WILLIAM FELDMAN, Primary Examiner.

20 JAMES L. JONES, JR., Examiner. 

1. IN A CHAIN WRENCH COMPRISING A HEAD HAVING A HANDLE CONNECTED THERETO, SAID HEAD INCLUDING A BIFURCATED PORTION AND A CAM, A CHAIN INCLUDING MEANS CONNECTING SAID CHAIN TO SAID HEAD BETWEEN SAID BIFURCATION, SAID CHAIN COMPRISING TRANSVERSE ROWS OF LINK PLATES HAVING LINKS PINS CONNECTING THE LINK PLATES TO EACH OTHER IN ROWS, SAID LINK PLATES TO EACH ROW BEING INTERDIGITATED WITH RESPECT TO THE LINK PLATES TO SAID ADJACENT ROW, EACH OF SAID LINK PLATES HAVING TEETH DISPOSED ON THE SAME SIDE OF SAID PLATE, THE TERMINUS OF SAID CHAIN EXTENDING THROUGH SAID BIFURCATION INTERMEDIATE SAID CAM AND SAID CONNECTING MEANS WHEREBY SAID CHAIN SUBSTANTIALLY CIRCUMSCRIBES AND GRIPS WITH SAID TEETH A WORKPIECE TO WHICH TORQUE IS TO BE APPLIED BY SAID WRENCH; THE IMPROVEMENT WHEREIN SAID 